Power transmission



Oct. 1, 1940. R. ERBAN 2,216,190

POWER TRANSMI SS ION Filed July 23, 1955 2 Sheets-Sheet l 06L 1, 194m, RERBAN 2,216,190

POWER TRANSMI SS ION Filed July 23, 1935 z'shfiets-sneet 2 INVENTOR,

Patented Oct. 1, 1940 UNITED STATES PATENT OFFICE 2,216,190 I POWERTRANSMISSION Richard Erban, New York, N. Y., assignor t Erban PatentsCorporation-New York, N. Y., a corporation of New York Application July23, 1935, Serial No. 32,694

4 Claims.

for, namely, (a) the apparatus becomes more effective in itsv operationas the speed increases and therefore is generally operated at a highspeed; and, (b) the power required increases with the speed.

It is therefore one of the objects of my invention to provide a variabletransmission wherein the efficiency of the transmission will increase asits ratio increases and will be at its maximum at top speed.

It is a further object of my inventionto provide a variable transmissionwherein its capability to transmit power with increasing speedscorresponds as closely as possible to the increasing power requirementsof the apparatus operated thereby.

Where the transmission is to be employed, as for example, insupereharging the motors of automobiles, flyingmachines and the like,the question of size and weight is of primary importance, and inautomobiles the question of cost is also a very determining factor. l

Therefore, it isa further object of my invention to provide avariabletransmission for operating centrifugacl" blowers, particularlyfor snperel'larging purposes, wherein the weight and size of thetransmission is reduced Without any decrease in its effectiveness inmeeting themquirements for supereharging, and this objective I attain,at least in part, by the attainment of the objects above set forth.

I have illustrated in the drawings one embodiment of my invention forthe attainment of these and other objectives not hereinabovespecifically pointed out, and in this embodiment the transmission isshown as comprising two units, one of "which is variable and serves tocontrol the ratio of transmission of the other. The other unitfwl'iichis herein disclosed as ofplanetary type, generally designed and devisedso as to give a speed increasing ratio always in excess of that which isrequired and slightly in excess of that which is required at top speedand always to do this with a relatively high efficiency.

The variable unit itself is so devised, designed and integrated with theplanetary unit as to permit of the employment of a variable unit of aconventional type, and of a size required for handling only a small partof the power passing through the transmission even at high speeds,without causing any substantial decrease in the efficiency of thetransmission as a whole.

In the embodiments herein disclosed, the output shaft of the planetarywhich is also the output shaft of the transmission, is taken off'theinnermost member of the planetary andthe'input power to the transmissionis applied to the intermediate element of the planetary, and the thirdor outside element of the planetary is adapted to rotate, under controlof the variable unitg it will be understood, however, that thisarrangement may be modified without departing from the scope of myinvention. i

For the attainment of another of the objects of my invention, I have oneelement of the variable .unit in driving connection with the outermember of the planetary unit and another member of the variable unit indriving connection with the input power shaft of the transmission sothat the power flow through the variable unit is from the outer memberof the planetary to one member of the variable unit, then to anothermember of the variable unit, and from this member of the variable unitback to the input power shaft;

For the attainment of these objects and such other objects as mayhereinafter appear or be i pointed out, I have illustrated severalembodiments of my invention in the drawings, wherein:

Figure 1 is a largely diagrammatic view in section through one form ofvariable speed transmission constructed in accordance with my inventionand driving an associated centrifugal blower mechanism:

Figures 2 and 3 are diagrams showing the rela tions in the velocities ofthe different parts of the transmission, each figure relating to aparticular setting of the ratio of the transmission:

Figure 4 is a side elevation partly in section of another embodiment ofmy invention, in which the planetary is of the external type; and

Figure 5 is a diagram, similarto thefdiagrams of Figures 2 and 3,showing the relation of the velocities in the embodiment of Figure 4.

As before stated, m transmission in general comprises a planetary gear,and a variable ratio transmission unit hereinafter always to beI'eferred to as the variable unit, so associated that under the mostusual condition of operation the main part of the power passes throughthe planetary gear and only a fraction through the variable unit. Toattain this end the innermost element of the planetary is connected tothe driven shaft, and its two other elements to the main drive shaft andthe variable unit respectively in such a manner that said two elementsturn in the same direction. The other side of the variable unit is alsoconnected to the main drive shaft. I have found that the best resultsare obtained by connecting the main drive shaft to the middle element ofthe planetary.

The principles involved will be better understood as the detaileddescription proceeds, but it is believed advisable to preface suchdescription by a brief discussion of the advantages attainable by theuse of my invention.

It is an important feature of my transmission, that while the highestspeed of the driven shaft may be a multiple of the speed of the maindriv,

ing shaft, the speed of the variable unit corresponding to this point ofhighest speed of the driven shaft is at its lowest point, andconsequently the power transmitted by said variable unit is very low; itmay be only 5% of the total power or even less.

As the speed of the driven shaft decreases, that of the variable unitincreases, but since the total power also decreases, the amount of powertransmitted through the variable unit never becomes more than a fractionof the maximum power required by the blower. To give figures from actualpractice, in a transmission, designed for a range of speed ratios inwhich the speed of the driven shaft varies from 12 to '7 times that ofthe drive shaft, and used with an airplane engine supercharger consuming70 horse power at its highest speed, the variable unit carries only 5.8horse power, or 8.3% at the 12:1 ratio, and not over 12.1 horse power,or 17.2% at the 7:1 ratio.

Since airplane blowers are normally operated under high speedconditions, and they are run at low speed only at the take off and partof the climb, so that the time for low speed operation is only a smallfraction of the total flying time, the size of the variable unit may beproportioned to the high speed requirements and the capacity of thevariable unit to stand an overload for short periods be depended on forlow speed requirements. It is found possible with my inventilon toeffect a reduction in weight of the variable transmission in comparisonto variable transmissions of heretofore known type, that amount to 1 formy invention as compared to 10 for the customary arrangement.

Before proceeding to the detailed description of the invention, it willbe emphasized that one of the important features thereof is that ofhaving the variably controlled element of the planetary rotating at aspeed which is slow as compared with the speed of either the'driving orthe driven shaft, and that as the speed of the variable unit decreases,the speed of the driven shaft increases. It is this feature that permitsthe use of a small variable unit in the control of an amount of powerthat would otherwise require a unit from 5 to 10 times its capacity.

The advantages of a small unit, besides a reduction in weight, obviouslyalso include reduced cost.

Upon viewing Figure 1 of the drawings it will be observed that I havethere illustrated, in connection with an airplane motor, a blower of the.type used on airplanes, denoted by A, and shown as driven by atransmission comprising a variable unit (to which, as a whole, referencecharacter B has been applied), associated with a planetary unit (towhich, as a whole, reference character C which is shown for the sake ofclearness.

has been applied) in a manner to be more fully pointed out in detail.

The planetary unit C is illustrated as of the gear type, although itwill be understood that it may be of other types, and is driven by theinput shaft [5, (which may be the main shaft of the airplane engine, asshown, or a shaft driven therefrom), to transmit the power thereof tothe output or blower shaft l6, by the arrangement which I will nowdescribe.

The input power shaft i5 is keyed to the hub 20 of the planetary carrier2!, of planetary C, which is provided with a set of shafts 22, upon eachof which is rotatably journalled a two stage planetary gear wheel 23.For the sake of clearness only one wheel 23 and one shaft 22 have beenshown. The larger gear 24 of the planetary wheel 23 is shown as drivingthe output shaft i6 by means of the gear teeth 11, on the inner end ofthe output shaft l6, meshing with the external gear teeth l8 carried by24. The smaller gear 25 of the planetary 23 is shown in drivingengagement with the outer gear ring 26 of the planetary transmission,the gear 25 having teeth 2? and the gear 26, internal teeth 28.

It will be understood that by the arrangement thus far described, thepower shaft l5 will cause theplanetary carrier 2| to revolve about theaxis of the input shaft l5. This causes a revolving movement, about theaxis of shaft H), of the shafts 22 carrying planetary gears 23. If theouter gear ring 26 were held stationary, it will be understood that dueto the engagement therewith of the smaller diameter gears 25, of thetwo-stage planetary gears 23, the latter would be caused to rotate abouttheir carrier shafts 22, and. thus transmit motion to the output shaft16 to drive the blower, because of the interengagement of teeth 88 ofgear 26 with teeth I! of shaft l6. The speed ratio at which the blowerwill be driven will be determined by the relative radii of the gears inmesh.

I will now describe an arrangement whereby I accomplish the followingadded results: (a) the ratio at which the planetary operates iscontrolled by a variable transmission, and (b) the power is sodistributed that only a small fraction of the power is delivered tooperate the variable unit for this controlling purposes, and thereforethe variable unit can be made of a size and of a capacity which is onlythat required to take care only of this fraction of the power deliveredby the input shaft.

This variable unit, denoted as a whole by B, comprises a pair of toricraces l0 and H, having therebetween a system of rollers I2, only one ofThe rollers are in adhesive contact with the races, and

are kept so under all conditions of load by an arrangement to behereinafter described, and serve to transmit power between the races. Asshown in full lines in Figure 1, the roller I2 is in such a positionthat the speeds of the races must be the same. If the roller is shiftedfrom the full line position to other positions the speeds of the racesand 42.

rangement similar to the one herein disclosed ly the frame M are capableof limited rotary movement, such movement being limited. by themovements of a member 40 to be hereinafter described, and such movementtaking place in response to the effect of torques passing throughrollers if on the frame I4.

The details of the mechanism for adjusting the inclination of therollers has not been illustrated, for the sake of clarity. Suchconstructions are well-known; by Way of example, I may refer to U. S.Patent1,999,543.

Race ii is shown as keyed to shaft 30, suitably journalled in the frameD of the device, as indicated at 32 and 34, and a gear 36 having teeth38 thereon adapted to mesh with external teeth 39 on the rim of gear 26,heretofore mentioned in connection with the planetary C, is also keyedto the shaft 30. Race H is further shown as held against axial movementby a collar 35 on shaft 39. Whereas race II is shown as keyed to shaftEll. race I!) is shown as mounted so as to be not merely rotatable inrelation to shaft 36, and to the sleeve 3| surrounding it, but to beaxially movable as well, and by providing a sufficient clearance betweenthe hub of this race and the sleeve 3!, it is also adapted for limitedangular movement in relation thereto, such angular movement permittingthe race to adjust itself in relation to the system.

Intermediate the race If! and the gear 36 is a system of parts of thetype customarily known as a torque-loader, the function of which is tosecure the adhesive driving contact'between the races iii and H androllers l2 under all condi-- tions of load. This it accomplishes bygenerating an axial pressure on race l0, increasing as the torquepassing through the system increases, for causing the race 19 to movetoward race H, and exert pressure on the intermediate rollers ill. Thissystem may comprise a member 40 fixedly associated, as by a key, withthe sleeve Bl, and a member at opposed thereto, and mounted in the frameD so as to be slidable but not ro- The member 42 is sage of sleeve .tltherethrough and clearance is provided so as to permit self-aligningangular movement of member 42 in relation to sleeve 3|. Each of members40 and 42 is provided with inclined pressure surfaces, those of membersll] being indicated at M, and those of members 42 at These surfaces arearranged in pairs,. the surfaces of each pair being oppositely inclinedso as to form a wedge-shaped depression, and opposed to each pair ofsurfaces of member ltl is a complementary pair of surfaces on member 62.Within each of the hollows so formed is located a pressure elemen til l,shown-as in the form of a ball. When relative rotation takes placebetween members it and 42, as when spiders M move under the action oftorques transmitted by rollers it these elements 44 will ride up on theopposed inclined surfaces ll and i3 andwill cause relative axialmovement between members The details of a torque loader ar are morefully illustrated and describedin U. S. Patent 1,585,140.

Member Ml is fixed in axial relation to race H, as will be more fullyexplained; and the result of relative rotation of members 4% and 42 isan axial movement of member 42 toward race ii, and a resulting axialmovement of race l toward race H, the movement of race l0 being effectedby the balls 46 interposed between member 42 and race l0, and serving totransmit axial pressure and movement to race l0, yet leaving the latterfree to rotate.

As shown in Figure 1, member 46 is prevented from moving away from raceII by a ball bearing comprising balls t and a race 46, the latterabutting against gear 36, which in turn is held in place against axialdisplacement away from race I l by any suitable arrangement, such as thebearing race 48 and the nut 50.

In order to transmit power between race it] and the input shaft it, Ishow a sprocket gear 58, journalled in bearings 56 carried by anextension 56 of the casing D; and this sprocket gear has a drivingconnection at 6b with the race is, and by means of a sprocket chain 62,with a gear 64, carried by the casing of a slip clutch Eli, the purposeof which is to limit the torques passing through the transmissions B andC, for which purpose it is arranged to transmit torques up to apredetermined value and to slip when the torques exceed this value.

With the aid of the foregoing description the operation of my devicewill now be understood, and its advantages will become clear.

As before stated, if the outer planetary member 26 were held stationarywhile the intermediate planetary member M were rotated, the driven shaftit would be rotated; and its direction of rotation would be the same asthat of member 2|, while its speed of rotation would be higher. If nowwe assume that the outer member 26 is allowed to rotate in the samedirection as and at a speed of rotation equal to that of theintermediate member 2|, the gear 25 no longer rolls within 26 and thewheel 23 is held fixed on its shaft 22, so that the driven shaft It nowturns with a speed of rotation identical with that of driving shaft l5,and the direction of rotation is also the same for both shafts.

If, starting with this speed and direction of rotation of the gear 26,the latter is now slowed down, a speeding up of the driven shaft 16results. It is therefore obvious that the lower the ratio setting of thevariable unit is, that is, the lower the speed of the driven gear 36 ofthe variable unit, the faster the rotation of the driven shaft [6.

It follows that the higher the speed at which it is desired to drive theblower A, and consequently the greater the power demands made upon it,the less the speed, and consequently the lower the relative powerconsumption of the vari able unit B. The efficiency of powertransmission therefore increases as the power output of the blowerincreases.

A graphical representation of the velocity relations will be found inFigures 2 and 3, in which 0 represents the outer member of theplanetary, P the planetaries and N the intermediate member or planetarycarrier of a planetary gear, while M represents the driven member. Forthe sake of simplicity the planetary gear corresponding to wheel 23 isshown as having only one stage. If a linear speed V0 is impressed on themember C, and a linear speed Vn, on the planetary carrier N, then thespeed Vm will represent the linear speed imparted to the periphery ofthe drivn member M, Vm being determined geometrically by the fact thatthe points of the velocity arrows V0, Va and Vm must all lie in astraight line. V0 and Vn being given, Vm is readily found.

A comparison of Figures 2 and 3 will show the effect of decrease in thedriven speed, as the speed of the outer member, determined by thevariable transmission, is increased and vice versa. It will further beobvious that the rate of increase of the speed ratio increases as V isdiminished.

In Figure 4 I have shown a modified form of transmission in which anexternal planetary arrangement is used instead of the internal planetaryarrangement of Figure 1. H indicates the driving shaft, carrying gearI25, and H6 indicates the driven shaft, carrying gear 1. The planetarycarrier is I2I; and 22 is indicative of a set of carrier shafts, eachhaving a unitary double gear comprising gears I24 and I25 carriedthereby. The variable unit is driven from the shaft H5 by chain I62passing over sprockets I58 and I64, associated respectively with thevariable transmission U and the drive shaft H5, and is connected to theplanetary carrier I2I by gear I39 on the latter, meshing with ear I46associated with the variable unit U.

It will be observed that whereas in Figure 1 the rotational speed of theplanetary carrier 2! is constant, or rather equal to the drive shaftspeed, in the construction of Figure 4, the planetary carrier isvariably driven, while the rotational speed of gear I26 is constant, orrather the same as the drive shaft speed.

The velocity diagram for this construction is shown in Figure 5. In thisdiagram Z indicates the driving member I26, Y the planetary gear shaftI22, and X the driven gear I". Va, the linear peripheral speed of I26may be assumed to be constant and V1, the linear speed of shafts I22, iscontrolled by the variable unit. V122, the linear peripheral speed ofthe driven gear II"! is again determined by the geometrical constructionused in Figures 2 and 3. Again we observe that V11, proportional to theoutput speed of the variable unit, is small compared to the load speedVa, and also that decrease of Vy causes an increase of V23, the ratio ofincrease itself increasing as Vy becomes smaller.

The dotted circles in Figure 5 indicate points of correspondence betweenthe diagrams of Figure 5 and Figure 2, and the constructions to whichthey relate. Therefrom it will appear that the axis of shaft I22 ofFigure 4 corresponds to the point of contact between the outer gear 26of Figure 1 and the planetary pinions 25. To show this equivalency Ihave indicated in Figure 5 in dotted lines a large circle, intended torepresent the outer gear 26 of Figure 1.

The contact point between gears I25 and I26 of Figure 4 corresponds tothe shafts 22 carrying the planetaries 25 of Figure 1.

The contact point between gears I24 and I1! of Figure 4 corresponds tothe contact point of gears 24 and gear teeth I! of driven shaft I6.

It will therefore be apparant that both planetary constructions embodythe same concept, and this concept may be referred to the constructionof Figure 1. In this figure the outer gear 26 may be termed theoutermost member, and the gear teeth I? or sun gear of the planetary,the innermost member, while the compound planetaries 23 may be termedthe intermediate member.

This terminology is the one that has been adopted in the claims, and,because of the equivalence of the constructions of Figures 1 and 4, ashereinabove pointed out, has been used in reference to either of them.

In defining the invention in the claims it has furthermore been foundnecessary to use the term speed of free rotation as applied to themember controlled by the variable unit. This may be defined as the speedthat the said controlled member would have if freed from the control ofthe variable unit and the driven shaft were held stationary, so that thespeed of the controlled member would be determined solely by the speedof rotation of the drive shaft I 5.

While I have herein disclosed two embodiments of my invention it will beunderstood that the same may be embodied in many other forms withoutdeparting from the spirit thereof as will be obvious to those skilled inthe art, and that the disclosure herein is not intended to be limitingin any sense, and that I do not limit myself in any way other than ascalled for by the prior art.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is:

1. For use in a supercharger having: a rotary impeller; a drive shaft; atrain of gears connecting the drive shaft to the impeller to transmitpower to rotate the impeller, the train including planetary and orbitgears; means to retain the gears of said train in mesh; a variable speedtransmission of the toric race and roller type; a power transmittingconnection between said variable transmission and said drive shaft, thepower transmitted by the variable transmission being ultimatelydelivered to said impeller; and means to increase the speed ratio ofsaid train of gears in response to decreased power transmitted by saidvariable transmission, said means including a constant speed ratiochange connection between one of said orbit gears and said variabletransmission whereby the effective power control by said variable speedtransmission is increased relatively to the power absorbed by saidimpeller.

2. For use in a supercharger having: a rotary impeller: a drive shaft; atrain of gears connecting the drive shaft to the impeller to transmitpower to rotate the impeller, the train including a planetary gear androtary carrier therefor and also including driving and driven gears;means to retain the gears of said train in mesh; a variable speedtransmission; a power transmitting connection between said drive shaftand said variable transmission, the power transmitted by the variabletransmission being ultimately delivered to said impeller; and means toincrease the speed ratio of said train of gears in response to decreasedpower transmitted by said variable transmission, said means includingconstant speed ratio change elements whereby the effective power controlby said variable speed transmission is increased relatively to the powerabsorbed by said impeller.

3. For use in a rotary pump construction having: a rotary impeller; adrive shaft, a train of gears connecting the drive shaft to the impellerto transmit power to rotate the impeller; means to retain the gears ofsaid train in mesh; a variable'speed transmission; a power transmittingconnection between said variable transmission and said drive shaft, thepower transmitted by the variable transmission being ultimatelydelivered to said impeller; and means to increase the speed ratio ofsaid train of gears in response to decreased power transmitted by saidvariable transmission, said means including constant speed ratio changeelements driven by a gear of said train of gears whereby the effectivepower control by said variable speed transmission is increasedrelatively to the power absorbed by said impeller.

4. For use in a rotary pump Construction having: a rotary impeller; adrive shaft, a train of gears connecting the drive shaft to the impellerto transmit power to rotate the impeller; means to retain the gears ofsaid train in mesh; a variable speed transmission of the race and rollertype; a power feed back connection between said variable transmissionand said drive shaft, the

clutch included in said power feed back connection; and means toincrease the speed ratio of said train of gears in response to decreasedpower 5 transmitted by said variable transmission.

RICHARD ERBAN.

